SpiceJet has placed a firm order for as many as 42 Boeing 737 MAX aircraft that offer fuel savings compared to its existing fleet of current-generation 737s, one source said.

Such an order would be worth $4.4 billion at list prices without adjusting for either inflation or price discounts.

The loss-making SpiceJet, which is looking for new investors, has also negotiated options to buy as many as 42 further jets depending on its future growth, the industry sources said, speaking on condition of anonymity.